EUVD-2026-43938
GHSA-r3m2-hccm-c492
Severity by source
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Local privilege escalation requiring an authenticated low-privileged user (AV:L/PR:L), low complexity, no user interaction, yielding full SYSTEM compromise (C:H/I:H/A:H).
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
2DescriptionCVE.org
Use after free in Windows Kernel allows an authorized attacker to elevate privileges locally.
AnalysisAI
Local privilege escalation in the Windows Kernel affects Windows 11 (24H2, 25H2, 26H1) and Windows Server 2025 (including Server Core), where an authorized attacker can exploit a use-after-free (CWE-416) memory-corruption condition to elevate privileges to SYSTEM. The flaw was reported by Microsoft, which has released a patch, and carries a CVSS 7.8 rating driven entirely by high confidentiality, integrity, and availability impact once local access is obtained. There is no public exploit identified at time of analysis and it is not listed in CISA KEV.
Technical ContextAI
The vulnerability resides in the Windows Kernel, the privileged core of the operating system that mediates memory management, scheduling, and hardware access for all user-mode processes. The root cause is a use-after-free (CWE-416): a kernel object is freed while a stale reference to it remains, and subsequent use of that dangling pointer lets an attacker who controls the reallocated memory corrupt kernel state. The CPE data scopes this to modern Microsoft platforms only - Windows 11 versions 24H2, 25H2, and 26H1, plus Windows Server 2025 and its Server Core installation - indicating the defect is present in current kernel code rather than legacy branches. Use-after-free in the kernel is a classic primitive for local elevation of privilege because successful exploitation typically yields arbitrary kernel read/write and ultimately SYSTEM-level code execution.
RemediationAI
Apply the Microsoft security update for CVE-2026-50436 (patch available per vendor advisory) to all affected systems - Windows 11 24H2/25H2/26H1 and Windows Server 2025 including Server Core - via the standard cumulative update; consult the MSRC update guide at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-50436 for the exact KB and build numbers, which were not provided in this data set. No specific vendor workaround is indicated for this kernel use-after-free, and none substitutes for patching. As compensating controls until the update is deployed, restrict the ability of untrusted or standard users to execute arbitrary code on affected hosts - enforce least privilege, application allow-listing (WDAC/AppLocker), and limit interactive/RDP logon on servers - since the attacker must already have local code execution to trigger the bug; note these controls reduce but do not eliminate exposure and can disrupt legitimate workflows.
More in Windows 11 Version 24H2
View allRemote code execution in Windows IKE Extension (Internet Key Exchange) via double free memory corruption allows unauthen
Windows Shell protection mechanism failure (CVE-2026-32202) allows remote attackers to perform spoofing attacks over a n
Local privilege escalation in the Microsoft Windows Kernel allows an unauthorized attacker to gain elevated (SYSTEM-leve
Local privilege escalation in the Windows Kernel lets an already-authenticated attacker corrupt kernel memory via a use-
Local code execution in the Windows DHCP Client service stems from a use-after-free (CWE-416) memory-corruption flaw aff
Local privilege escalation in the Microsoft Windows Kernel allows an already-authenticated attacker to elevate to SYSTEM
Local code execution in the Windows Media component of supported Windows 10, Windows 11, and Windows Server (2016 throug
Local privilege escalation via heap-based buffer overflow in the Windows Message Queuing (MSMQ) Queue Manager component
Local privilege escalation in Microsoft Windows Win32K lets an authenticated low-privileged user corrupt kernel heap mem
Local privilege escalation in the Windows NTFS file system driver lets an authenticated low-privileged user win a race c
Elevation of privilege in the Windows Hyper-V virtual network switch (VMSwitch) lets an authenticated attacker operating
Remote code execution in Microsoft Windows Remote Desktop (RDP) allows an unauthorized network attacker to run arbitrary
Same weakness CWE-416 – Use After Free
View allSame technique Use After Free
View allShare
External POC / Exploit Code
Leaving vuln.today